This invention relates to self-propelled sprinkler systems and more particularly to drive systems for moving sprinkler systems over a field.
Considerable effort has been expended by the self-propelled sprinkler system manufacturers to develop reliable drive subsystems for propelling a srinkler system over a field. The sprinkler system operates in a very adverse environment that includes a great deal of moisture, soft ground, and high vegetation. Additionally, the industry is extremely competitive requiring that any reliable drive subsystem additionally be quite economical.
Most circular irrigation equipment systems include a plurality of spaced towers along the water conduit for supporting and propelling the conduit across the field. Generally the tower is supported by two tandem wheels that are spaced on opposite sides of the center line of the water conduit. Some manufacturers have developed individual electric drive motor systems for each tandem wheel. An example of such a system is illustrated in the Bryant et al U.S. Pat. No. 3,662,776 granted May 16, 1972. Other manufacturers in an effort to economize and reduce the number of electric motors required to drive the system have utilized a single electrical motor placed intermediate the tandem wheels with dual drive shafts extending from the electrical motor gearbox outward in both directions to the wheel assemblies. Examples of such concepts are illustrated in the Fry U.S. Pat. No. 3,831,682 granted Aug. 27, 1974; the Reinke U.S. Pat. No. 3,623,662 granted Nov. 30, 1971 and the Zimmerer et al U.S. Pat. No. 3,730,435 granted May 1, 1973. One of the major problems associated with such systems is that the drive shaft frequently becomes entangled with the vegetation. After a while the entangled vegetation is capable of stopping the movement of the drive shafts which completely stops the entire system.
A further development in this regard is illustrated in the Raso et al U.S. Pat. No. 3,771,719 granted Nov. 13, 1973. The Raso patent describes a drive system having a single motor adjacent one of the wheels with a drive shaft extending from one wheel to the other tandem wheel to drive the wheel in unison from a single drive motor. Likewise such a system enables the vegetation to become entangled with the interconnecting drive shaft.
One of the principal objects of this invention is to provide a sprinkler system that is quite economical using a single drive motor per tower while at the same time being able to prevent the high vegetation from becoming entangled in the drive system and rendering it inoperative.
An additional object of this invention is to provide an improved tower drive subsystem for a sprinkler system utilizing a single drive motor per tower in which the connecting drive shafts are connected to respective gear reduction units without utilizing universal joints.
An additional object of this invention is to provide an improved tower drive system utilizing a single electric motor per tower in which the drive system may be accurately aligned to eliminate the need for misalignment compensating mechanisms such as universal joints.
A further object of this invention is to provide a tower drive system that utilizes a single drive motor per tower that is considerably more reliable and capable of more extended life than previous systems.
A further object of this invention is to provide an improved tower drive system utilizing a single drive motor per tower that is capable of smoothly starting and stopping without the conventional jerks generally associated with constant speed electrical drives.
A still further object of this invention is the safety afforded to operating personnel by preventing inadvertant contact with moving parts, as specified in regulations proposed by OSHA for farm field equipment.
These and other objects and advantages will become apparent upon reading the following detailed description of a preferred embodiment.